Performance of unreinforced masonry and infilled RC buildings during the 2015 Gorkha, Nepal earthquake sequence

On 25 April 2015 at 11:56 local time a moment magnitude (Mw) 7.8 earthquake struck Nepal, with the epicentre in Gorkha District (north-west) of Kathmandu and south of the China border. More than 390 aftershocks followed with magnitude 4 or higher, including a magnitude 6.7 and a 7.3 earthquake on 26 April and 12 May 2015, respectively. The epicentre of the main shock was approximately 34 km (21 mi) east-southeast of Lamjung, Nepal, and its hypocentre was at a depth of approximately 15 km. Over 500,000 buildings were identified by the Nepal Government as fully damaged and approximately 300,000 buildings as partially damaged, including both private and Government buildings. The affected buildings were primarily concentrated in the Gandaki, Bagmati and North of Janakpur Zones, between Pokhara and Mt. Everest, also including the capital Kathmandu. However the effects of the earthquake were observed in many buildings throughout Nepal. As part of earthquake reconnaissance an international team of experts visited urban and rural affected sites in Nepal. The team closely examined the performance of unreinforced masonry buildings, including cultural heritage structures, and infilled masonry RC buildings. Details of construction techniques and observed earthquake damage are summarised and commented on herein.